The longterm goals of this project are to determine the modes of action of TPA in several cell systems. Several approaches will be used to try to define the receptor or receptors which bind TPA and to determine where they may be located. Among these will be observation of TPA effects on specifically labeled surface proteins, examination of specific receptors (such as beta adrenergic receptors) and the molecular events in binding and transduction which are inhibited by TPA, and genetic manipulation and selection to produce TPA resistant mutants and identify the steps which are modified. It is reasonable to believe that TPA action in one cell type (Y1 adrenal cell) depends on a protein kinase. Since much of TPA's activity is signaled by changes in membrane function, two mechanisms which may control or initiate such function will be examined - phosphorylation and methylation. A series of experiments on several cell types involving glucose transport, cell growth and induction of plasminogen activator will explore whether these processes are always linked to one another. Finally, we will use both TPA induction and basal levels of plasminogen activator in various types of leukemic cells to explore the possibility of using these as an aid in classification of these diseases. Also, we hope to use mezerein to detect events which may be unique to TPA induced changes in cell function by examining mezerein effects on those processes affected by TPA.